<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title></title>
    <style type="text/css">
        * {
            padding: 0;
            margin: 0;
            list-style: none;
            border: 0;
        }

        .all {
            width: 500px;
            height: 200px;
            padding: 7px;
            border: 1px solid #ccc;
            margin: 100px auto;
            position: relative;
        }

        .screen {
            width: 500px;
            height: 200px;
            /*overflow: hidden;*/
            position: relative;
        }

        .screen li {
            width: 500px;
            height: 200px;
            overflow: hidden;
            float: left;
        }

        .screen ul {
            position: absolute;
            left: 0;
            top: 0px;
            width: 3000px;
        }

        .all ol {
            position: absolute;
            right: 10px;
            bottom: 10px;
            line-height: 20px;
            text-align: center;
        }

        .all ol li {
            float: left;
            width: 20px;
            height: 20px;
            background: #fff;
            border: 1px solid #ccc;
            margin-left: 10px;
            cursor: pointer;
        }

        .all ol li.current {
            background: yellow;
        }

        #arr {
            display: none;
        }

        #arr span {
            width: 40px;
            height: 40px;
            position: absolute;
            left: 5px;
            top: 50%;
            margin-top: -20px;
            background: #000;
            cursor: pointer;
            line-height: 40px;
            text-align: center;
            font-weight: bold;
            font-family: '黑体';
            font-size: 30px;
            color: #fff;
            opacity: 0.3;
            border: 1px solid #fff;
        }

        #arr #right {
            right: 5px;
            left: auto;
        }
    </style>
</head>
<body>
<div class="all" id='box'>
    <div class="screen">
        <ul>
            <li><img src="images/1.jpg" width="500" height="200"/></li>
            <li><img src="images/2.jpg" width="500" height="200"/></li>
            <li><img src="images/3.jpg" width="500" height="200"/></li>
            <li><img src="images/4.jpg" width="500" height="200"/></li>
            <li><img src="images/5.jpg" width="500" height="200"/></li>
        </ul>
        <ol></ol>
    </div>
    <div id="arr"><span id="left">&lt;</span><span id="right">&gt;</span></div>
</div>
<script>
    //需求 实现一个 完整的轮播图
    //找人
    var box = document.getElementById("box");
    var screen = box.children[0];
    var ul = screen.children[0];
    var ol = screen.children[1];
    var ulLis = ul.children;//所有的广告
    //箭头
    var arr = document.getElementById("arr");
    var left = document.getElementById("left");
    var right = document.getElementById("right");
    //1.动态生成结构
    //1.1根据图片数量动态生成按钮
    for (var i = 0; i < ulLis.length; i++) {
        var li = document.createElement("li");
        li.innerHTML = i + 1;
        ol.appendChild(li);
    }
    var olLis = ol.children;//所有的按钮
    olLis[0].className = "current";
    //1.2克隆第一张广告 放到最后
    var firstImg = ulLis[0].cloneNode(true);
    ul.appendChild(firstImg);
</script>
</body>
</html>
